Annotate CC-to-Automation Lua-script and fix start/pos offset.

scripts/midi_cc_to_automation.lua

@@ -5,23 +5,32 @@ ardour { ["type"] = "EditorAction", name = "MIDI CC to Plugin Automation",
 }
 
 function factory () return function ()
-	-- find target parameters
+	-- find possible target parameters, collect them in a nested table
+	--   [track-name] -> [plugin-name] -> [parameters]
+	-- to allow selection in a dropdown menu
 	local targets = {}
 	local have_entries = false
 	for r in Session:get_routes ():iter () do -- for every track/bus
+		if r:is_monitor () or r:is_auditioner () then goto nextroute end -- skip special routes
 		local i = 0
-		while 1 do -- iterate over all plugins on the route
+		while true do -- iterate over all plugins on the route
 			local proc = r:nth_plugin (i)
 			if proc:isnil () then break end
-			local plug = proc:to_insert ():plugin (0)
+			local plug = proc:to_insert ():plugin (0) -- we know it's a plugin-insert (we asked for nth_plugin)
-			local n = 0
+			local n = 0 -- count control-ports
 			for j = 0, plug:parameter_count () - 1 do -- iterate over all plugin parameters
 				if plug:parameter_is_control (j) then
-					if plug:parameter_is_input(j) then
+					local label = plug:parameter_label (j)
-						local nn = n
+					if plug:parameter_is_input (j) and label ~= "hidden" and label:sub (1,1) ~= "#" then
+						local nn = n --local scope for return value function
+						-- create table parents only if needed (if there's at least one parameter)
 						if not targets [r:name ()] then targets [r:name ()] = {} end
+						-- TODO handle ambiguity if there are 2 plugins with the same name on the same track
 						if not targets [r:name ()][proc:display_name ()] then targets [r:name ()][proc:display_name ()] = {} end
-						targets [r:name ()][proc:display_name ()][plug:parameter_label(j)] = function () return {["p"] = proc, ["n"] = nn} end
+						-- we need 2 return values: the plugin-instance and the parameter-id, so we use a table (associative array)
+						-- however, we cannot directly use a table: the dropdown menu would expand it as another sub-menu.
+						-- so we produce a function that will return the table.
+						targets [r:name ()][proc:display_name ()][label] = function () return {["p"] = proc, ["n"] = nn} end
 						have_entries = true
 					end
 					n = n + 1
@@ -29,11 +38,13 @@ function factory () return function ()
 			end
 			i = i + 1
 		end
+		::nextroute::
 	end
 
 	-- bail out if there are no parameters
 	if not have_entries then
 		LuaDialog.Message ("CC to Plugin Automation", "No Plugins found", LuaDialog.MessageType.Info, LuaDialog.ButtonType.Close):run ()
+		targets = nil
 		collectgarbage ()
 		return
 	end
@@ -46,30 +57,30 @@ function factory () return function ()
 		{ type = "heading", title = "Target Track and Plugin", align = "left"},
 		{ type = "dropdown", key = "param", title = "Target Parameter", values = targets }
 	}
-	local od = LuaDialog.Dialog ("Select Taget", dialog_options)
+	local rv = LuaDialog.Dialog ("Select Taget", dialog_options):run ()
-	local rv = od:run()
 
-	if not rv then
+	targets = nil -- drop references (the table holds shared-pointer references to all plugins)
-		od = nil collectgarbage ()
+	collectgarbage () -- and release the references immediately
-		return
+
-	end
+	if not rv then return end -- user cancelled
 
 	-- parse user response
 
-	local midi_channel = rv["channel"] - 1
+	assert (type (rv["param"]) == "function")
+	local midi_channel = rv["channel"] - 1 -- MIDI channel 0..15
 	local cc_param = rv["ccparam"]
-	local pp = rv["param"]()
+	local pp = rv["param"]() -- evaluate function, retrieve table {["p"] = proc, ["n"] = nn}
 	local al, _, pd = ARDOUR.LuaAPI.plugin_automation (pp["p"], pp["n"])
-	od = nil collectgarbage ()
+	rv = nil -- drop references
-	assert (al)
+	assert (not al:isnil ())
 	assert (midi_channel >= 0 and midi_channel < 16)
 	assert (cc_param >= 0 and cc_param < 128)
 
 	-- all systems go
 	local add_undo = false
 	Session:begin_reversible_command ("CC to Automation")
-	local before = al:get_state()
+	local before = al:get_state () -- save previous state (for undo)
-	al:clear_list ()
+	al:clear_list () -- clear target automation-list
 
 	-- for all selected MIDI regions
 	local sel = Editor:get_selection ()
@@ -77,14 +88,21 @@ function factory () return function ()
 		local mr = r:to_midiregion ()
 		if mr:isnil () then goto next end
 
-		local bfc = ARDOUR.DoubleBeatsFramesConverter (Session:tempo_map (), r:position ())
+		-- get list of MIDI-CC events for the given channel and parameter
 		local ec = mr:control (Evoral.Parameter (ARDOUR.AutomationType.MidiCCAutomation, midi_channel, cc_param), false)
 		if ec:isnil () then goto next end
 		if ec:list ():events ():size () == 0 then goto next end
 
+		-- MIDI events are timestamped in "bar-beat" units, we need to convert those
+		-- using the tempo-map, relative to the region-start
+		local bfc = ARDOUR.DoubleBeatsFramesConverter (Session:tempo_map (), r:start ())
+
+		-- iterate over CC-events
 		for av in ec:list ():events ():iter () do
+			-- re-scale event to target range
 			local val = pd.lower + (pd.upper - pd.lower) * av.value / 127
-			al:add (bfc:to (av.when), val, false, true)
+			-- and add it to the target-parameter automation-list
+			al:add (r:position () - r:start () + bfc:to (av.when), val, false, true)
 			add_undo = true
 		end
 		::next::
@@ -97,12 +115,11 @@ function factory () return function ()
 		Session:commit_reversible_command (nil)
 	else
 		Session:abort_reversible_command ()
-		LuaDialog.Message ("CC to Plugin Automation", "No data was converted. Was a MIDI-region selected?", LuaDialog.MessageType.Info, LuaDialog.ButtonType.Close):run()
+		LuaDialog.Message ("CC to Plugin Automation", "No data was converted. Was a MIDI-region with CC-automation selected? ", LuaDialog.MessageType.Info, LuaDialog.ButtonType.Close):run ()
-		collectgarbage ()
 	end
+	collectgarbage ()
 end end
 
-
 function icon (params) return function (ctx, width, height, fg)
 	local txt = Cairo.PangoLayout (ctx, "ArdourMono ".. math.ceil (width * .45) .. "px")
 	txt:set_text ("CC\nPA")